1977, 1978, 1979 & 1981 Mainframe Zork in Confusion

I have the 1977 (sort of) and the 1978 version patched up and running under Matthew Russotto’s Confusion. See my repository for code.

Mainframe Zork for Confusion

These are the currently known MDL sources of the mainframe Zork. I have slightly changed the code to make it runnable in Matthew Russottos’s Confusion, the MDL emulator, “a MDL interpreter which works just well enough to play the original Zork all the way through”. The status of the different
versions here are listed below.


There is a couple of files missing from this version, most notably the “melee”-file. I have tried to modify and use the “melee”-file from the 1978-version. But there is still bugs in this version. You can play it all the way until you encounter the troll, when the game crashes.


This is a more complete version. I’ve patched it up and I believe it’s playable all the way to the end. There was one strange bug that made the game crash if you tried doing something in a dark room (like LIGHT LAMP). This could be a bug in the original source, but it’s not present in the compiled game of this version that is playable on the PDP-10 ITS emulator. I have fixed with he fix that’s used in the later versions.


I have not started patching this version that I belive is very similar to the 1981 version


This is the source files that Bob Supnik released 2003. The version here is with Matthew Russotto’s patches to make it work under Confusion.

Playing the games

To play the games you’ll need Confusion that can be found at IF-Archive, Matthew Russotto’s homepage or Benjamin Slade’s patched version. Benjamin Slade also have a blog post about compiling it. The Win32-version (by David Kinder) contains a precompiled version that works fine on these Windows versions that I tried: Windows7 (32-bit) and Windows10 (64-bit).

When you have Confusion running in the same directory as the source, you type (in Confusion):

<FLOAD "run.mud">

This loads all the code, compiles, save a copy of “/MDL/MADADV.SAVE” and starts the game. You can always start the game this way, but when you have the “MADADV.SAVE” or another “*.SAVE”-file you can start it directly from the prompt by (for example):


or from inside Confusion:


There is only one save slot in Zork, but you can always make your own copies in the OS. If you find this cumbersome, remember that originaly on PDP-10 ITS the game quit when you saved and you had to wait 24h before you could restore and continue playing.

Thanks to Tim Anderson, Marc Blank, Bruce Daniels and Dave Lebling for creating the original Zork and to Matthew Russotto for building Confusion.


I have updated the repository with a patched version of Confusion and a patched Fortran version of Zork (Dungeon 3.2b) by Bob Supnik. I have tested and succeeded to build both in CygWin and Ubuntu 64-bit.

The repository is here.

Now the version from 1979-12-11 is fixed and playable.

This version is almost identical with the 1981 version. See the README.md for details.

Hopefully there will be an even earlier (summer 1977) version released in the PDP-10 ITS project soon.

Are they talking about a summer-1977 version? I haven’t been following the discussion.

Yes. Apparently Lars Brinkhoff have files from 1977-06-08 to 1977-07-02 that he hopes can be released soon. See this issue.

I think all versions are playable now. Here is a rough timeline with what was added between the different versions:

500 point version, no end-game.
This version still has a bug that writes two messages when you pick up objects. I’m not sure if this is an original bug or something that is introduced by Confusion.

500 point version + end game (100 points)

616 point version + end game (100 points)
New puzzles:

  • Canary egg + brass bauble + clockwork canary
  • Dready room (blue palantir)
  • Coal chute (red palantir)
  • Bank area
  • Royal puzzle

616 point version + end game (100 points)
This version is almost identical to the 1979 one. There is only some minor bugfixes.

The 1977-12-12 version of Zork is now fully reconstructed and playable. I played the whole game just now and finished with all 500 points!

There was a game-breaking bug in the autotake logic (TAKE-IT) in np.mud that made you always pick up takable things, even those with the flag NO-TAKE. This is a problem with the boat, because it has to be on the ground for you to be able to BOARD it. But that’s fixed now.

For other changes that was made to make it possible to play this under Confusion, see the README.file.

The parser is interesting. It is noticable that this is an early attempt. It, for example, understands ALL but not multiple itrems seperated with a comma. You can’t refer to objects with IT and you can’t type a lone adjective. I think it is charming and you can trace the development of the parser through the different versions of Zork and then on through Infocom.

Note that this version lacks the end-game (not yet developt I guess) and therefore the ending is a bit anticlimatic. You get the max score and then can just continue to wander around in the world.

My reconstructed version of the game is here.

Next up is a playthrough of the 1978-01-24 version!

By the way. Is this a possible way to die in Zork 1?

There is a pile of leaves on the ground.
>get leaves
A grating appears on the ground.
>light match
One of the matches starts to burn.
>light leaves with match
The sight of someone carrying a pile of burning leaves so offends
the neighbors that they come over and put you out.
Do you want me to try to patch you?

About the lack of an ending:

Your ranking when you got 500 points is “Cheater” and in the 1978-01-24 version this message is in the code, when the end-game is not loaded:

Suddenly a sinister wraithlike figure, cloaked and hooded, appears
seeming to float in the air before you.  In a low, almost inaudible
voice he says, "I welcome you to the ranks of the chosen of Zork. You
have persisted through many trials and tests, and have overcome them
all.  One such as yourself is fit to join the even the Implementers!"
He then raises his oaken staff, and chuckling, drifts away like a
wisp of smoke, his laughter fading in the distance.

Unfortunately, as the wraith fades, in his place appears a tastefully
lettered sign reading:

	      Soon to be Constructed on this Site
		A Complete Modern Dungeon Endgame
		    Designed and Built by the
		  Frobozz Magic Dungeon Company

This leads me to believe that the implementers were just a little bit ahead of the players and frantically added things to the game.

Kind of. This is from release 88, but other than spacing the message is almost the same as in release 2 so I’m just assuming it didn’t change in between:

In disturbing the pile of leaves, a grating is revealed.

One of the matches starts to burn.

The leaves burn, and so do you.

   ****  You have died  ****

The “Solid Gold” release does reinstate some things from the mainframe version, e.g. a slightly expanded version of the Flood Control Dam #3 guidebook, and you die if you try to “PLAY object”, where object is an actor (even “PLAY ME”) though the output is a bit buggy. But I don’t see anything about the neighbors in that version either.

Someone must have really liked that “PLAY …” joke, because there are versions of it in Zork III and Enchanter (though neither seem to work quite as intended), Infidel (I can’t find any object to use it on) and - somewhat bizarrely - Cutthroats:

You are so engrossed in the role of the desk clerk that you kill yourself, just
as he would have done!

   ****  You have died  ****

Too bad.
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I like the more unpolished look in mainframe Zork. like this from the matchbook, where Mr. TAA and Mr. MARC is quite identifiable.

>read matchbook
        [close cover before striking BKD]

You too can make BIG MONEY in the exciting field of
                PAPER SHUFFLING!
Mr. TAA of Muddle, Mass. says: "Before I took
this course I used to be a lowly bit twiddler.
Now with what I learned at MIT Tech I feel really
important and can obfuscate and confuse with the best."
Mr. MARC had this to say: "Ten short days ago all I could
look forward to was a dead-end job as a doctor.  Now
I have a promising future and make really big Zorkmids."

MIT Tech can't promise these fantastic results to everyone.
But when you earn your MDL degree from MIT Tech your future
will be brighter. Send for our free brochure today.

And of course, there is the ASCII-art…

|                                        |
|          ||||||||||        LORD        |
>         !||||      |      DIMWIT       <
|         ||||    ---|     FLATHEAD      |
|         |||C     CC \                  |
>          ||||       _\                 <
|           ||| (____|                   |
|            ||      |                   |
>             |______|       Our         <
|               /   \     Excessive      |
|              /     \      Leader       |
>             |       |                  <
|             |       |                  |
|                                        |
>    G.U.E. POSTAGE        3 Zorkmids    <
|                                        |

              /      Gold Zorkmid        \
             /  T e n   T h o u s a n d   \
            /        Z O R K M I D S       \
           /                                \
          /        ||||||||||||||||||        \
         /        !||||          ||||!        \
        |          |||   ^^  ^^   |||          |
        |          |||   OO  OO   |||          |
        | In Frobs  |||    <<    |||  We Trust |
        |            || (______) ||            |
        |             |          |             |
        |             |__________|             |
         \                                    /
          \    -- Lord Dimwit Flathead --    /
           \    -- Beloved of Zorkers --    /
            \                              /
             \       * 722 G.U.E. *       /
              \                          /
|         _______         |
>  One   /       \     G  <
| Lousy /         \    U  |
> Point |   ___   |    E  <
|       |  (___)  |       |
>       <--)___(-->    P  <
|       / /     \ \    o  |
>      / /       \ \   s  <
|     |-|---------|-|  t  |
>     | |  \ _ /  | |  a  <
|     | | --(_)-- | |  g  |
>     | |  /| |\  | |  e  <
|     |-|---|_|---|-|     |
>      \ \__/_\__/ /      <
|       _/_______\_       |
>      |  f.m.l.c. |      <
|      -------------      |
>                         <
|   Donald Woods, Editor  |
>     Spelunker Today     <
|                         |
| 1  0   0          GREAT UNDERGROUND EMPIRE         1  0   0 |
| 1 0 0 0 0                                          1 0 0 0 0|
| 1 0 0 0 0                                          1 0 0 0 0|
| 1  0   0                  DIMWIT                   1  0   0 |
|                      ||||||||||||||||                       |
|                      ||   __  __   ||            B30332744D |
|                      ||  -OO  OO-  ||                       |
|       IN  FROBS      \||    >>    ||/     WE  TRUST         |
|                       ||  ______  ||                        |
| B30332744D             |  ------  |                         |
|                        \\________//                         |
| 1  0   0    Series       FLATHEAD     LD Flathead  1  0   0 |
| 1 0 0 0 0   719GUE                     Treasurer   1 0 0 0 0|
| 1 0 0 0 0                                          1 0 0 0 0|
| 1  0   0        One Hundred Royal Zorkmids         1  0   0 |

I thought “Mr. Anderson” and “Dr. Blank” in Zork I were pretty identifiably, too. :grinning:

Other than that, the main difference in the mainframe version of the matchbook seems to be the bit about sending for a free brochure.

Which reminds me, there was a post on the Data Driven Gamer blog comparing three versions of Zork I. Most of the differences were of course parser responses, but there were a couple of changes to the game text as well. E.g. the references to Hunt the Wumpus and EBCDIC were removed.

(Oddly enough, Zork II kept the EBCDIC reference.)


You’re right. My excuse is that been a while since a played Zork 1.

Oh, thanks. I hadn’t seen that one.

I always thought the one with the lantern was the best drawn, but I could never figure out… What does the “f.m.l.c.” on the base mean?

Edit: The only interpretation I’ve found that makes any kind of sense is “First Match Losers Consolation”. (At least it seems much more likely than “Fetal Mouse Liver Cell”.)

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I would have guessed someting like, Frobozz Magic Lantern Company.


Ah, that makes even more sense. I should have thought of that!

By the way, there is a pretty significant change in the Flood Control Dam #3 guidebook when comparing Zork I to mainframe Zork: In Zork I, it says that “This impressive structure is composed of 370,000 cubic feet of concrete”. In mainframe Zork, it’s “composed of 3.7 cubic feet of concrete”.

A Marc Egazarian asked about that in the Summer 1985 edition of The New Zork Times. The answer he got was that “It may be impossible to build a dam with such a small piece of concrete, but this is a fantasy remember? Actually, it was intended as a joke; it is not a typo.” I wonder if the joke wasn’t funny enough to be retained in Zork I, or if the joke’s on me for believing them. :grinning:

1 Like

I’ll take MIT Engineering Jokes for $800, Alex.